DISK SURFACE DENSITY TRANSITIONS AS PROTOPLANET TRAPS

摘要: The tidal torque exerted by a protoplanetary disk with power-law surface density and temperature profiles onto anembedded embryois generally anegative quantity that leads to the embryoinward migration. Here we investigate how balance is affected at radial jump. jump has two consequences:(1)Itaffects thedifferential Lindbladtorque.Inparticular,ifthediskismerelyemptyontheinnerside,the differential Lindblad almost amounts large negative outer torque. (2) It affects corotation torque, which very sensitive local gradient of density. In particular, if depleted on inside occurs radially over few pressure scale heights, positive ismuchlargerthan inapower-lawdisk.Weshow bymeans ofcustomized numerical simulations low-massplanetsembedded inprotoplanetarynebulaewithasurfacedensity thesecond effect isdominant; is, largely dominates edge central depletion, even shallow one. Namely, about 50% 3–5 thicknesses suffices cancel out total As consequence, type I migration low-mass objects reaching should be halted, all these trapped there provided some amount dissipation present in prevent saturation. turbulence, induces jitter planet semimajor axis, under conditions trapping process overcomes trend turbulence induce stochastic across disk. We show cavity inner ratio efficiently traps embryos from 1 15 M� , any radius up 5 AU object, same profile as minimum mass solar nebula (MMSN). Shallow transitions require light disks trap embryos. case MMSN, this could happen parts (r < 0:03 AU). discusswhereinaprotoplanetarydiskonecanexpectasurfacedensityjump.Thiseffectcouldconstituteasolutionto well-known problem buildup first protogiant solid core takes much longer than its toward object. Subject headings: accretion, accretion — hydrodynamics methods: planetary systems: formation